Electron-beam poling of piezoelectric polymer electrets

Irradiation with a monoenergetic electron beam is demonstrated as a poling technique for piezoelectric polymer electrets. Poling-current measurements during electron irradiation indicate a ferroelectric polarization of typically about 0.1 C/m2. The generated nonuniform polarization profiles are probed by means of laser-induced pressure pulses. It is found that the thickness of the unpoled sample volume is proportional to the 1.5th power of the electron energy used. The proposed method thus allows the fabrication of polymer electrets with a polarization zone of predetermined thickness for, e.g., application in flexure-mode devices